Why is it that when you believe that Ф-ing is good, you thereby have a reason to Ф?
Sometimes this question is posed antagonistically to cognitivists/realists about normativity. The thought, I think, is that typically when one stands in the belief relation to a proposition one does not thereby have a motivation to do something. What’s so special about the normative propositions, asks the non-cognitivist/anti-realist. Why is standing in the belief relation to normative propositions motivating for action?
It seems that there is an easy answer. Desires are motivating. Nobody doubts this. And, desires are evidence for the truth of normative propositions, or at least we use desires as evidence for the truth of normative propositions.
Consider. Someone asks you whether it would be good to increase the sales tax to improve the roads. What do you do? That is, as a conscientious epistemic agent yourself, what goes on in your head in trying to determine whether imposing the tax would be good? One thing I do is put myself in a hypothetical situation in which I am confronted with the choice, and then introspect for my consequent hypothetical desires. If I find that I have the strong desire to choose to impose the tax, I take that as evidence that it would be good to impose the tax. If I find I have a strong desire to choose not to impose the tax, I take this as evidence that not imposing the tax would be good.
In general, I take my desire of X to Y to be evidence that X is better than Y. Defeasible evidence, perhaps only a bit of evidence, but evidence nevertheless.
Thus, we expect a correlation. We expect that the normative propositions I believe often will have motivational force. The reason is that for many of the normative propositions I believe I have used my desires as evidence for whether the normative propositions are true. If I didn’t have the desires I have, I wouldn’t have had as much evidence for the normative propositions I believe, so, probably, I wouldn’t have believed as I do.
Using desires as evidence is especially important in the normative sphere where it is harder to get evidence for the truth of propositions. It is harder to get evidence that Ф-ing is good than it is to get evidence that Ф-ing is typically done by women.
On my view, it isn’t constitutive of believing that Ф-ing is good that one thereby has a motivation to Ф. One could believe that Ф-ing is good and yet have no motivation at all to Ф. But that seems to me appropriate, even desirable.
I take it that this puzzle is supposed to be deeper than my dealings with it. Am I missing something?